Magnetic NiFe2O4 3D nanosphere photocatalyst: Glycerol-assisted microwave solvothermal synthesis and photocatalytic activity under microwave electrodeless discharge lamp

In this study, NiFe2O4 (NFO) nanocrystalline powder was synthesized using a glycerol-assisted microwave solvothermal process followed by annealing. In comparison with the traditional preparation method, this method does not require addition of any precipitate-controlling agents. The structural properties of NFO were characterized via different techniques, such as X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and ultraviolet?visible diffuse reflection spectra. The results suggested that the NFO crystal was a three-dimensional (3D) porous nanosphere with a diameter of approximately 400 nm, and the glycerol added during the preparation process played a crucial role in the formation of 3D nanospheres. The photocatalytic activity of NFO was evaluated by the degradation of methylene blue (MB) in a microwave electrodeless discharge lamp (MEDL) system. Additionally, the mechanism of MB photocatalytic degradation was studied. The results suggest that 88.6% of the MB degraded within 10 min under MEDL irradiation, and the mineralization rate reached 55%. The main active species of MB degradation were e-, h+, and ?O2? . In addition, the cycle catalysis experiment confirmed the reusability of NFO 3D nanospheres. We believe that the NFO 3D nanospheres can serve as efficient photocatalysts suitable for MEDL systems.

Automated summary

In this study, NiFe2O4 (NFO) nanocrystalline powder was successfully synthesized using a novel method, exhibiting a three-dimensional porous nanosphere structure. The NFO showed efficient photocatalytic degradation of methylene blue (MB) in the MEDL system, with high cycling stability confirmed through repeated catalysis experiments.